The present invention relates to a pump with a motor in which a pump housing and a motor housing are connected by caulking.
As a connecting structure capable of easily attaching a motor to a driven-side device such as a small pump, there is a connecting structure using “caulking” as disclosed in Japanese Utility Model Laid-Open No. 6-57063 (literature 1). The connecting structure disclosed in literature 1 is formed from a plurality of connecting pieces projecting from a motor housing and a plurality of through holes formed in the attached body of the driven-side device.
The motor housing is formed into a cylindrical shape with a closed bottom having a bottom portion to be attached to the driven-side device. A bearing storage portion formed from a cylindrical body is provided by drawing at the central portion of the bottom portion of the motor housing. The bearing storage portion is configured to store a bearing that rotatably supports the rotating shaft of the motor. The connecting pieces are formed by press working by cutting and raising portions of the bottom portion located outside the bearing storage portion in the radial direction. In addition, the connecting pieces are provided at positions that divide the bottom portion into two equal parts in the circumferential direction.
The attached body of the driven-side device is formed into a cylindrical shape with a closed bottom having a bottom portion overlaid on the bottom portion of the motor housing. A center hole in which the above-described bearing storage portion is inserted and a plurality of through holes in which the connecting pieces are inserted are formed in the bottom portion of the attached body.
To attach the attached body to the motor housing, first, the connecting pieces of the motor housing are inserted into the through holes of the attached body. Then, the bearing storage portion of the motor housing is inserted into the center hole of the attached body, and the bottom portion of the motor housing and the bottom portion of the attached body are overlaid on each other. After that, the distal ends of the connecting pieces are bent and caulked, thereby fixing the attached body to the motor housing.
The connecting structure disclosed in literature 1 has two problems to be described later. As the first problem, the reaction in the rotation direction, which acts in the motor housing, is received by only the connecting pieces. For this reason, the connecting pieces need to be firmly formed, and the workability in caulking the connecting pieces becomes low.
As the second problem, the manufacturing cost of the motor housing becomes high. This is because two types of compression molding need to be performed for the motor housing. The two types of compression molding are press working to cut and raise the connecting pieces and drawing to mold the bearing storage portion.